Abstract: A centrifugal pump for pumping a mixture of abrasive particles in a liquid has a casing affording a cylindrical pumping chamber with an inlet and outlet, and an impeller of circular form disposed in the chamber for rotation about the longitudinal axis thereof, with radially extending vanes for drawing the mixture into the chamber through the inlet and expelling it via the outlet, the dimensions of the impeller and pumping chamber being such that the clearances between the impeller and chamber wall are small. The inside wall of the chamber, and the impeller carry an outer layer of rubber or like abrasive-resistant material.