Contact assemblies for electrochemical processing of microelectronic workpieces. The contact assemblies can comprise a support member that includes an inner wall which defines an opening configured to receive the workpiece and a plurality of contacts. The individual contacts include a conductor and a cover. The conductor can comprise a proximal section projecting inwardly into the opening relative to the support member, a distal section extending from the proximal section, and an inert exterior at least at the distal section. The cover comprises a dielectric element that covers at least the proximal section of the conductor, but does not cover at least a portion of the distal section of the core. The exposed portion of the distal section of the core, accordingly, defines a conductive contact site for contacting a conductive layer (e.g., a seed layer) on the workpiece.