DIAGNOSIS The rotary pump is cavitating or has a foreign object stuck in the impeller. This is a high-precision vibration pump, not a typical coffee maker vibratory pump.
FIX Immediately stop the brew cycle. Unplug the machine. Remove the water tank and inspect the intake screen at the bottom for debris like scale or coffee grounds. Clean it thoroughly.
IF THAT DIDN'T WORK The pump itself may have worn internal bearings. This is a repair that requires disassembly. You need a replacement pump, part number SP0010052 for the Ulka pump assembly.
HEADS UP Running the machine with this noise will destroy the pump. Do not continue use until the sound is resolved.