The paper deals with a study of the mechanism of erosion wear of the blades of pitched blade impellers in a solid-liquid suspension to determine the influence of the blade material (hardness) on its wear rate. A four-blade pitched blade impeller (pitch angle alpha = 30 degrees), pumping downwards, was investigated in a pilot plant fully baffled agitated vessel with a water suspension of corundum. The metallic blades of the impeller were made from various materials of different hardness, i.e. from aluminiurn alloy (Vickers hardness 34 HV 10) via rolled brass and construction steel to stainless steel (194 HV 10).