A threshing and separating system (130) for an agricultural harvester (100) includes: a rotor (131) configured to rotate about a rotor axis (RA)； a rotor cage (210) at least partially enclosing the rotor, the rotor cage including a tailings return inlet (212) formed therein and configured to couple to a tailings return elevator (148)； and at least one concave (132) coupled to the rotor cage and defining a plurality of concave perforations (233). An insert opening (214) formed in the rotor cage is at least partially circumferentially aligned with the tailings return inlet relative to the rotor axis. A threshing insert (240, 640) is removably coupled to the rotor cage (210), the threshing insert (240, 640) at least partially covering the insert opening (214) and being positioned such that material from the tailings return inlet (212) travels past the threshing insert (240, 640) before reaching the concave (132).
