A chemical mechanical polishing pad that includes a polishing layer having a polishing region and containing a plurality of grooves extending at least partially into the polishing region. The insert is formed by a composition of the substrate of about 5-7 wt % Co, about 0. The first plunger is disposed such that an end thereof is capable of extending into a main cap recess and the second plunger is disposed such that an end thereof is capable of extending into an auxiliary cap recess.