A sanitary insert unit is provided having a jet regulator which has a housing with a housing inlet and a housing outlet, and a jets splitter in the housing interior. The jet splitter protrudes partially into a diffuser ring, delimiting an annular channel therebetween. The diffuser ring is insertable into an outlet-side housing part of the housing until an annular step on the outer circumference of the diffuser ring bears on an inlet-side mating surface on an outlet-side housing part. A circumferential locking cam on an outer circumference of the diffuser ring is movable into locking engagement with a locking groove provided on an inner circumference of the outlet-side housing part. The locking cam has a run-on bevel which interacts with a mating bevel upstream from the locking groove in an insertion direction that has a greater angle of inclination with respect to a longitudinal axis in comparison with the run-on bevel.