A reinforcing interface between the stator and its housing in a progressing cavity pump is created from ribs extending inwardly into the stator from the housing inner wall that can be longitudinally oriented or spirally oriented. Alternatively, the housing wall can have grooves into the inner wall that are made more bulbous further into the housing wall from the groove inlets so that when filled with stator material a long and continuous grip is obtained with either the wall groove embodiment or the internal rib embodiment.