Wajam is a Potentially Unwanted Program, not a big threat. From their website :
Add relevant social results and recommendations from your friends and contacts, to your regular search results.
McAfee flagged wajam_validate.exe as an Artemis threat last year and someone from the company asked for the file to be checked by the labs - see
The file got the all-clear. Doesn't stop all those third-rate malware-removal sites from saying it's a dangerous virus though :-)