Hi Catherine,
If Abraham Lesiuk was born in 1988, he arrived Palestine at 36 years old in 1924 and was almost 60 at Independence War in 1948. It is not impossible, but I think it is most probably that was one of his sons who died in that war.
There is a site Izkor (in hebrew) with almost all died soldiers in Israeli wars - the surname Lesiuk is not there.
Instead that, I found a man Abraham Lesiuk (and probably his family) that changed his surname to Ben-Zeev (Wolf' Son) - please see the Oficial Palestine Gazette of 23/06/1938 (original page 711, PDF page 17).
I checked also Ben-Zeev surname at Izkor' site, and found a man that fall in 1948 with this surname. His name was David, was born in Odessa to Abraham and Ruchama and arrived Israel/Palestine in 1923. You can try google translate on the page itself. He doesn't appears with his family in the Gazette, but may be he changed his name in another oppurtunity.
Hope this info helps you.

CesarYeudkin
Israel

researching:
YEUDKIN/YUDKIN, SCHEIMAN from Gomel in Belarus
DUGATKIN, SHMUKLER, KOHON, BERKUN, OSCHEVEROF/OSHEVEROV, SILBERT from Kherson Guvernia / Ukraine