In an embodiment, a rotary drill bit includes a bit body having a leading end structure configured to facilitate drilling a subterranean formation, and a plurality of cutting elements mounted to the bit body. At least one of the plurality of cutting elements includes a polycrystalline diamond compact (“PDC”) comprising a cemented carbide substrate including a first cemented carbide portion and a second cemented carbide portion bonded to the first cemented carbide portion and exhibiting an erosion resistance that is greater than the first cemented carbide portion. The PDC further comprises a polycrystalline diamond (“PCD”) table bonded to the first cemented carbide portion. The PCD table includes a plurality of bonded diamond grains exhibiting diamond-to-diamond bonding therebetween, with the plurality of bonded diamond grains defining a plurality of interstitial regions.