A polyelectrolyte dispensing polishing pad, a process for its production and a method of polishing, e.g., chemical mechanical polishing (CMP), a substrate such as a semiconductor wafer, are provided. The pad is usable for CMP planarization of an oxide or metal layer on the wafer. The pad has a polishing layer of erodible binder material containing uniformly distributed therein both abrasive particles and a water soluble ionizable electrolyte substance such as a polyelectrolyte, such that during polishing the binder material incrementally erodes and the abrasive particles and electrolyte substance incrementally release into direct contact with the substrate. The electrolyte substance inhibits CMP removal of silicon nitride, e.g., as a stop layer, under an upper oxide or metal layer, such that the upper layer is selectively polished and the CMP stops on the stop layer leaving the latter intact.