In World War Z, the Israeli soldier that Gerry rescues introduces herself as Segen, which I see is simply Hebrew for the rank of lieutenant. Why is she reluctant to provide her real name?
Is she similarly reticent in the book?
You're right about the name "Segen", which is not real name used in Hebrew, but only the rank. I don't know why she wouldn't use her name.
However, I can answer your second question easily - she wasn't, because she doesn't exist in the book. The movie has very little relation to the book, other than taking a global and geopolitical look at a zombie apocalypse. The book is built as a post-apocalypse UN report, not as a personal narrative/adventure of a specific operative.
This may have also been a play on words. In Hebrew is does mean 'Lieutenant' while in German it means 'Blessing'
Mayhap they were giving her some implied history in the name/title that her family may have survived another nasty bit of history?