An earth boring bit has rotary cutters with embedded tungsten carbide inserts and milled steel teeth. The teeth and the grooves are first milled into the cutters, with the grooves extending between bases of the teeth, parallel to the crests of the teeth. Hard facing is applied to surfaces of the teeth and the grooves, and then the cutters are heat treated. Insert sockets are drilled into the teeth, centrally disposed in crests of the teeth. The tungsten carbide inserts are secured in the insert sockets, aligned for forming cutting profiles with respective ones of the milled teeth. The cutters are preferably frustoconically shaped and used for a rotary cone rock bit, and the tungsten carbide inserts configured as chisel-shaped inserts having crests which are aligned parallel to the crests of the milled steel teeth.