Hubcap for a hub of a wheel assembly

A hubcap for a hub of a wheel assembly includes a body configured to couple to the hub. The body is formed from a first material having a first hardness, and the body has a port extending along a path through the body from a port inlet to a port outlet. The hubcap also includes an insert disposed within the port. The insert includes internal threads configured to engage corresponding external threads of a plug, the insert is formed from a second material having a second hardness, and the second hardness is greater than the first hardness. Furthermore, the port includes a seal-engaging surface configured to engage a seal of the plug, and each interface between the first material and the second material along a plug-facing interior surface of the path is positioned downstream from the seal-engaging surface.