The theft-protected screw part in the form of a nut or a screw has a free end region and a ring-shaped depression formed at the end region for the engagement of a wrench for rotation the screw part. Viewed from radially outside to radially inside, the depression is delimited by an outer edge, a bottom and an inner edge. The outer edge forms outer abutment surfaces and the inner edge forms inner abutment surfaces for the wrench. The screw part is composed of a main part and an insert. The main part has a protrusion, which is located within the inner edge. The insert is designed in a ring shape, has a hole for accommodating the protrusion and forms the inner abutment surfaces.