I recently created the admin.py based in the Django Project Document:
https://docs.djangoproject.com/en/dev/topics/auth/customizing/#django.contrib.auth.models
Put this in your UserChangeForm:
password = ReadOnlyPasswordHashField(label=("Password"), help_text=("Raw passwords are not stored, so there is no way to see " "this user's password, but you can change the password " "using this form."))