It's possible this Python 3 pip is installed as pip3; try
pip3 install <module>
Another way to install using pip is as follows:
python -m pip install <module>
Finally, from inside Python or IPython, one can also pip install:
>>> import subprocess
>>> subprocess.call('pip install <module>', shell=True)
If none of these work and you are still stuck, say how you installed Python and pip.