The invention relates to a machine part comprising a first physical component, wherein: the first physical component is configured for moving relative to a second physical component; the first physical component has a first surface with a contact area for physical contact with the second physical component; the first physical component is shaped spatially complementarity to the second physical component at the contact area, and a polyelectrolyte layer is present on the first surface at a location of the contact area. The invention further relates to a machine comprising the present machine part and the second physical component. In addition, the invention relates to the use of a polyelectrolyte layer to reduce the friction between the first physical component and the second physical component, and a rolling-elements bearing.