PURPOSE: To manufacture a component more easily at a lower cost than before by providing a base substance material having a desired component shape and the prescribed hardness and a titanium nitride layer covering the base substance material hardened to obtain the prescribed surface hardness.

CONSTITUTION: An insert 28 is formed with a base substance material made of high-speed alloy tool steel such as M2 steel. The base substance material is formed into a desired shape for the insert 28 by a conventional means, it is hardened and tempered by conventional processes, then the insert 28 is hardened to achieve the hardness in the range of about 62-65 in the Rockwell C scale. A thin film of titanium nitride is covered to the hardened insert 28 to attain the surface hardness of about 85 in the Rockwall C scale. The insert 28 thus obtained is manufactured much more easily at an extremely lower cost than the conventional insert made of solid tungsten carbide.