Say you only have some WNN numbers and Linux shows serial numbers in /dev/disk/by-id?
Give this a spin (assuming you have something left of the drive to query:
Warning: hdparm switches can and do change, read the man page before attempting this.
You might wreck data if you mistype the command. You have been warned
hdparm -I /dev/sdX (where X is the drive you want to get the WNN).
You should find it near the end of the output. This should allow you to match the serial number (also in the output), to the WNN on the drive case.