Injection molding apparatus having a cavity insert (10) with integral inner and outer portions (136, 138) having a cooling fluid flow channel (166) extending therebetween. In a preferred embodiment, the cooling fluid flow channel (166) is formed by a groove (164) machined in the outer surface (162) of the inner portion (136). This brings the cooling fluid flow closer to the cavity (66) and improves cooling efficiency and reduces cycle time.