Yes, there is. They hypothesize that this material works because the ceramic spheres vibrate inside the flexible matrix of the aluminum foam, damaging the grinding wheel. A thinner foam will have less ability to flex, and smaller spheres will be have less momentum to use against the wheel.

Plus, if you watch the video of them grinding the material (https://static-content.springer.com/esm/art%3A10.1038%2Fs415...), you can see that the grinding wheel penetrates over half an inch before it begins to be destroyed.

For comparison I was learning about medieval armor recently. Steel breastplates are about 2mm at their thickest, typically. So that's a rather heavy duty armor idea you have.

Real question then is how it would fare against bullets and piercing attacks. Cutting is only one possible threat, and usually not the biggest threat. Knife resistant bullet proof vest are already a thing, so how would this be better?