Recent Spitzer observations have revealed presence of near-IR excesses in spectra of more than thirty white dwarfs showing signs of significant metal enrichment in their atmospheres. These near-IR excesses have been naturally interpreted as resulting from reprocessing stellar emission by the compact, optically thick disks of dusty debris. The prevalent idea for their origin is the tidal disruption of asteroids scattered by massive unseen planets providing evidence for existence of the latter around white dwarfs. This circumstellar material has also been proposed as the cause of high-Z element pollution of the host white dwarf atmospheres. Such systems provide the best and accurate probes of the bulk composition of the extrasolar planetary bodies available to us. I will provide an overview of observations and theory in this rapidly developing area, and will describe recent progress in understanding the transfer of the high-Z material from the compact circumstellar debris disk onto the white dwarf surface.