A method of remanufacturing a fluid end block of a well stimulation pump includes cleaning an interior surface of a body of the fluid end block. The interior surface defines a chamber, a plunger passage in communication with the chamber, an intake passage in fluid communication with the chamber, and a discharge passage in fluid communication with the chamber. The interior surface is made from a base material. The interior surface of the fluid end block is cold-worked to produce a compressive residual stress layer within the body. A coating layer made from a non-metallic material is applied to at least a portion of the interior surface of the body. The non-metallic material is different from the base material.