There are lubricated O-ring seals between the moving parts. The elastic O-ring is seated in a precisely machined grove and slightly compressed during assembley. There should be no nicks, burrs, or scratches at the metal surfaces over which the O-Ring moves. The gap between stationary and rotating parts is filled by the O-ring. The gas pressure should move the O-ring closer to the gap.
See the images at the bottom of page 6 and 9 of this O-ring handbook PDF.
The EMU Maintenance Kit for the Apollo Suits contains a tool for O-ring removal and pads for lubrication:
From the Apollo Operations Handbook EMU.
But there is no information about O-rings used for rotating joints.