There is now provided a body coated with at least one diamond layer on a substrate of cemented carbide or cermets. The substrate is before the diamond coating process provided with spotwise occurring particles containing an element either being any of W, Ta, Ti, Mo Cr, V, Nb, Mg, Ca, Na, K or, preferably, any of B, Si, S, Al or P. These particles are dispersed at a density giving an average distance between two particles of 20 .mu.m or less, preferably 5 .mu.m or less.