Walk Across a Keyboard

Python 2, 83 bytes

lambda s:re.findall('.*?'.join(s),'qwertyuioplkmnjhbvgfcxdsza'*len(s))[0]
import re

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Walks the entire keyboard until the word is written.

Python 2, 274 bytes (optimal solution)

296 300 302 308 315 319 324 327 328 430 432 bytes

-4 bytes thanks to mypetlion

from networkx import*
i=input()
M,z='qwertyuiop  asdfghjkl   zxcvbnm'.center(55),i[:1]
G=from_edgelist([(M[e],M[e+h])for h in[-1,1,11,12,-11,-12]for e in range(44)if' '!=M[e]and' '!=M[e+h]])
for y,x in zip(i,i[1:]):z+=[shortest_path(G,y,x)[1:],list(G[y])[0]+y][x==y]
print z

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This solution gives the shortest possible output. The keyboard is transformed into a graph used to find the shortest path to compute the output string:

puzzles     --> poiuhbvcxzazxcvbhjklkiuytres
programming --> poiuytrtyuioijhgtresasdcvbnmkmkijnbg
code        --> cvbhjioijhgfde
golf        --> ghjiolkjhgf
yes         --> ytres
hi          --> hji
poll        --> polpl

Japt -g, 23 bytes

;D·ÎÔ+D·Årí)pUl)fUq".*?

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Takes input as an array of capital letters. Very similar to the other answers otherwise.

Explanation:

;                          :Set D to the keyboard layout
 D·Î                       :Get the first row of keys
    Ô                      :Reversed
     +                     :Concat
      D·Å                  :The other two rows
         rí)               :Interleaved
            p              :Repeat that string
             Ul)           : A number of times equal to the length of the input
                f          :Get the substrings that match
                 U         : The input
                  q".*?    : joined with ".*?"
                           :Implicitly output just once of the matches