An inserted powder injection molding (IPIM) method has been developed to overcome the size limitation ( < 10 mm) in the part production with powder injection molding process. In this method, the part called insert is placed into the mould and the feedstock is injected onto it and then the part is sintered. With this method it is possible to produce parts from different materials by using inserts. In this study, bonding of WC-Co feedstock and AISI 4340 insert during the sintering process was investigated by IPIM method using Ni interlayer. In EDS analyses, the most diffused element was determined as W depending on the concentration difference. When the intermediate zone was examined, it was observed that the Ni interlayer was infiltrated along 10 mm towards the WC-Co side. Meanwhile, on the AISI 4340 insert side, a diffusion zone which is 35 mu m( )wide was determined. As the shear strength of the intermediate zone is increased, Ni interlayer thickness and sintering time is increased. The highest shear strength came out to be 266.5 MPa in the 240 min sintering time by using 100 mu m Ni interlayer.