Effects of particle velocity, impact angle and particle size and shape on erosive behavior of Fiberglass Reinforced Plastic (FRP) and Polyethylene were investigated. Experiments were carried out with two particle velocities (18 and 32 m/s) and different impact angles ranging from 15 to 90 degrees. Silica sands with sizes of 75, 150 and 300 μm was utilized as erodent to study effects of sand shape and size. Results revealed erosion data of FRP and Polyethylene are similar to ductile materials as they display maximum erosion ratio at 30 degrees impact angle. However, Polyethylene showed an interesting behavior at 75 and 90 degrees; sand particles were embedded into the specimen and mass gain of specimen has been observed. 3D scan of wear patterns of specimens was obtained by 3D profilometer in order to evaluate the erosion depth and wear pattern of the surface.