diffusion of boron into the coated sides as shown in fig7 binder gradients in cemented tungsten carbides may be created by generation of gradients of an additive e g c b or n it is known that alteration of binder compositions will result in property changes in the cemented tungsten carbides for example significant hardness gradients were previously found in low cobalt content wc u2014 co samples that had been dyanite u2122 treated as shown in fig1 accordingly the local concentration gradients in boron as seen in fig8 are expected to result in local hardness gradients indeed hardness gradients in boron diffused wc u2014 co were detected in these samples albeit not very large data not shown the low hardness gradients observed in this example is most likely due to the relatively high cobalt contents in the starting cemented carbide samples because the degree of binder gradient created will be relatively less significant when the starting binder concentration is high the above description illustrates some embodiments of the invention which relate to inserts having localized material property changes some embodiments of the invention relate to dill bits having inserts that include local variations in material properties therein the drill bits may be fixed cutter drill bits or roller cone drill bits in addition some embodiments of the invention relate to methods for generating localized and or asymmetric variations in a material property of an insert fig1.