Abstract: On both heels of a racing plate a boss is formed having a top surface lying substantially flush with the top surface of the shoe, and an upwardly facing opening including a shallow recess and a mortise extending completely through the shoe is formed in each boss for receiving an insert. The insert formed of abrasion resistant material has a capital which lies in the recess, and a tenon which slides snuggly into the mortise and is held in place by a resilient O-ring. The insert capital supports the side walls of the recess and the recess walls exclude dirt from wedging between the capital and recess floor and lifting out the insert. A calk is made by forming a cleat on the insert capital; without a cleat, the insert is a wear plate whose top surface is flush with the top surface of the boss, providing a zone of increased wear resistance to decrease the wear of the heels.