An improved ball CHECK VALVES for use in positive displacement subsurface pumps used in the petroleum industry for pumping crudes characterized in part by a high degree of suspended solid particles. In accordance with the present invention, the ball Check Valves comprises a valve seat and a valve ball wherein the valve seat is comprised of a hollow cylindrical body defining an orifice through which fluid passes wherein the hollow cylindrical body is provided with an insert at the orifice of the hollow cylindrical body which forms the valve seat. In accordance wih the present invention, the insert is formed of a material having a hardness greater than the hardness of the material from which the valve ball is formed which material in turn is characterized by a high resiliency, a modulus of elasticity of between 0.1