An earth-boring bit and a method for forming a bit

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The present invention provides a bit with cutting structures or inserts that include diamond particles, in which the diamond-impregnated inserts are surrounded by substantially diamond-free support members. The diamond-impregnated inserts are manufactured separately from the bit body. Once formed, the diamond-impregnated inserts are affixed to the substantially diamond-free support members on bit body by brazing or other means of attachment. The total thermal exposure of the diamond particles during manufacture in accordance with the present invention is significantly lower than the total manufacturing-related thermal exposure in previously known diamond-impregnated cutting structures. Furthermore, the substantially diamond-free support members allow the bit to continue cutting through a formation without an increased contact area, as experienced by bits with diamond-impregnated ribs. Thus, the operating life of the cutting structures, and therefore the life of the bit itself, is increased.