Abstract: A rotary pump includes an impeller mounted on a shaft (12) supported for rotation in bearings. A bearing and bearing casing assembly (26) proximate the impeller is prone to ingress of undesirable matter. A shield assembly (40) includes the shaft (12) and a shield (40) rotatable with the shaft and positioned intermediate the impeller and the bearing assembly (26). The shield comprises an integral, moulded, disc (42) and composite rim (44), which includes a lip (50) having an inwardly proud beading (52) normally touching an outer periphery (34.1) of the bearing assembly. A cowl (48) surrounds the lip with clearance when the shaft (12) rotates. The beading (52) dilates under centrifugal force to provide running clearance.