A process for modifying the face of a putter including the steps of milling out recess in a portion of the face, inserting a carrier strip coated on opposites with adhesive and inserting a plastic insert plate with the same dimensions as the recess. The insert plate is formed with an outward side having a group of closely spaced parallel V-shaped grooves running in one direction and another group of closely spaced parallel V-shaped grooves running in an intersecting direction, the grooves defining a plurality of pyramids having flat tops. The invention may also be described as a putter having such an insert and a plastic insert per se, described above.