If you want to use different class names, you need to modify the default configuration.
Add those lines to your AppBundle/Resources/config/pimcore/config.yml
:
members:
# for the user class
user:
adapter:
class_name: 'customer' # default was 'MembersUser'
# for the group class
group:
adapter:
class_name: 'group' # default was 'MembersGroup'
# for the sso identity class
# only available if you're using the SSO feature
sso:
adapter:
class_name: 'identity' # default was 'SsoIdentity'
Tip: Add this to a separate config file.