The cam and lifters are toast. Review your break-in procedure, did the engine fire up immediately and go to 1500-2000 RPM and stay there for some time? If not the cam and lifters were damaged immediately. What spring pressure are you running? What brand of lifters? Cam? Lots of cam lube?
I think you have it backwards, the rockers didn't cause the lifter failure, the cam went first, causing slack and pounding the rockers out.
All that metal went into the oil sump and through the engine. Flush the system and change the oil and filter twice after the cam change. Best would be disassembly and inspection.