After building dockerfile: ModuleNotFoundError: No module named 'numpy'

I have to run the python program in Redhat8. So I pull Redhat docker image and write a Dockerfile which is in the following:

  FROM redhat/ubi8:latest
  RUN echo "nameserver 9.9.9.9" >> /etc/resolv.conf && mkdir /home/spark && mkdir /home/spark/spark && mkdir /home/spark/ETL && mkdir /usr/lib/java && mkdir /usr/share/oracle

  # set environment vars
  ENV SPARK_HOME /home/spark/spark
  ENV JAVA_HOME /usr/lib/java

  # install packages
  RUN 
    echo "nameserver 9.9.9.9" >> /etc/resolv.conf && 
    yum install -y rsync && yum install -y wget && yum install -y python3-pip && yum 
    install -y openssh-server && yum install -y openssh-clients && 
    yum install -y unzip && yum install -y python38 && yum install -y nano 
    # create ssh keys
    RUN 
    echo "nameserver 9.9.9.9" >> /etc/resolv.conf && 
    ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa && 
    cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys && 
    chmod 0600 ~/.ssh/authorized_keys
    # copy ssh config
    COPY ssh_config /root/.ssh/config
    COPY spark-3.1.2-bin-hadoop3.2.tgz /home/
    COPY jdk-8u25-linux-x64.tar.gz  /home/
    COPY instantclient-basic-linux.x64-19.8.0.0.0dbru.zip /home
    COPY etl /home/ETL/

    RUN 
    tar -zxvf /home/spark-3.1.2-bin-hadoop3.2.tgz -C /home/spark && mv -v 
    /home/spark/spark-3.1.2-bin-hadoop3.2/* $SPARK_HOME && tar -zxvf /home/jdk-8u25-linux-x64.tar.gz -C /home/spark && mv -v /home/spark/jdk1.8.0_25/* $JAVA_HOME && unzip /home/instantclient-basic-linux.x64-19.8.0.0.0dbru.zip -d /home/spark && mv -v /home/spark/instantclient_19_8 /usr/share/oracle && echo "export JAVA_HOME=$JAVA_HOME" >> ~/.bashrc && 
   echo "export PATH=$PATH:$JAVA_HOME/bin:$SPARK_HOME/bin:$SPARK_HOME/sbin:/usr/share/oracle/instantclient_19_8" >> ~/.bashrc && echo "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/share/oracle/instantclient_19_8" >> ~/.bashrc && echo "PYTHONPATH = $PYTHONPATH:/usr/bin/python3.8" >> ~/.bashrc && echo "alias python=/usr/bin/python3.8" >> ~/.bashrc

  #WARNING: Running pip install with root privileges is generally not a good idea. Try `python3.8 -m pip install --user` instead.
  # so I have to create a user
  RUN echo "nameserver 9.9.9.9" >> /etc/resolv.conf 
  RUN useradd -d /home/spark/myuser myuser
  USER myuser
  WORKDIR /home/spark/myuser
  ENV PATH="/home/spark/myuser/.local/bin:$PATH"
  RUN   
  python3.8 -m pip install --user pandas &&  
  python3.8 -m pip install --user cx-Oracle && 
  python3.8 -m pip install --user persiantools && 
  python3.8 -m pip install --user pyspark && 
  python3.8 -m pip install --user py4j && 
  python3.8 -m pip install --user python-dateutil && 
  python3.8 -m pip install --user pytz && 
  python3.8 -m pip install --user setuptools && 
  python3.8 -m pip install --user six && 
  python3.8 -m pip install --user numpy


   # copy spark configs
  ADD spark-env.sh $SPARK_HOME/conf/
  ADD workers $SPARK_HOME/conf/
  
  # expose various ports
  EXPOSE 7012 7013 7014 7015 7016 8881 8081 7077

Also, I copy and build the dockerfile with this script:

  #/bin/bash

  cp /etc/ssh/ssh_config .
  cp /opt/spark/conf/spark-env.sh .
  cp /opt/spark/conf/workers .
  sudo docker build -t my_docker .
  echo "Script Finished."

The dockerfile built without any error. Then I make a tar file from the image that made with this command:

  sudo docker save my_docker > my_docker.tar

After that I copy the my_docker.tar to the another computer and load it:

  sudo docker load < my_docker.tar
  sudo docker run -it my_docker

Unfortunately, when I run my program inside docker container, I receive errors about python package like numpy,pyspark,pandas.

  File "/home/spark/ETL/test/main.py", line 3, in <module>
  import cst_utils as cu
  File "/home/spark/ETL/test/cst_utils.py", line 5, in <module>
  import group_state as gs
  File "/home/spark/ETL/test/group_state.py", line 1, in <module>
  import numpy as np
  ModuleNotFoundError: No module named 'numpy'

I also try to install the python packages in the docker container and then commit the container.But, when I exit from the container and enter again, there is no python package installed.

Would you please guide what is wrong with my way?

Any help is really appreciated.